According to the prior art, the pilot carries out this check using the data of the page of the flight plan provided by the input and display or Multipurpose Control and Display Unit (MCDU) provided in the instrument panel, that is to say in the head down position of the cockpit.
In a known way an MCDU unit is one of the two interfaces provided to allow the pilot to have dialogue with the FMS (Flight Management System), which is an on-board computer. The other interface is an ND (Navigation Display) display screen upon which the flight path followed by the aircraft is shown, according to a chosen navigation mode (ARC or ILS for example). Whatever the type of representation of the flight path may be, the waypoints referenced in the flight plan which remain to be passed over appear on it. This screen is placed in the average head position.
The MCDU input and display unit comprises a keyboard and a screen and is placed in the head down position. It allows a dialogue between the flight management system and the pilot. This console, placed in the head down position, in particular allows him to enter the waypoints defining the flight plan and possibly to modify this flight plan.
The page of the flight plan is called up by the pilot using the keys of the keyboard (or of the screen) of the MCDU unit. This page is displayed on the screen. It normally displays, for all of the referenced waypoints of the active flight plan, various associated flight parameters, provided or calculated by the FMS (Flight Management System) on-board computer. These flight parameters are generally presented in line over two pages, considering the size of the screens. Depending on the number of referenced waypoints of the flight plan, the pages are also scrolled horizontally in order to display the various reference points. As shown in FIG. 1, the pilot can thus read, for each referenced point, the time of passing UTC over the point, and the cruising speed SPD and altitude ALT at that point, real for the points already passed, or estimated for the points to come, the heading TRK and the distance to travel between a referenced point and the following point, on a first page p1. By calling up a complementary page p2 on the display screen by means of control buttons provided for this purpose, he can read other data such as, for example, the speed and direction of the wind (not shown). He can in particular read the EFOB (Estimated Fuel On Board) data estimating the quantity of fuel remaining on board. At destination, that is to say the point referenced LMG in the example, the EFOB data is equal to the quantity of fuel remaining at destination, generally called EXTRA. The fuel quantity and more particularly the portion constituting the fuel reserve for the mission is calculated so that, according to the predicted average flight conditions for the journey, this EXTRA data is positive.
The calculation of the EFOB estimation and fluctuation data at each referenced waypoint of the flight plan is carried out by the on-board computer, the FMS, and is displayed for each referenced waypoint on the page of the flight plan. This calculation is based on the real consumption data available and on predictions according to the foreseen flight conditions over the journey. The EFOB data allows the pilot to monitor the fluctuations of the consumption during the mission. The pilot can derive from the EFOB data the quantity of fuel remaining at destination on the basis of the fuel quantity at each of the referenced points. However, in order to determine the quantity remaining on board at a given time in the mission, he must again extrapolate the values between the preceding passed referenced point and the next referenced point to be passed over. If these two points are very distant from each other, the result is very inaccurate.
The consumption monitoring procedure carried out by the pilot thus proves to be very fastidious and results in the pilot holding his attention, in the head down position, on the screen of the MCDU input and display unit, that is to say in him diverting his attention from the head up field of view in order to read the data and to make interpolation calculations. It has also been observed that the calculations that the pilot has to make can be inaccurate. Another complexity factor of this monitoring procedure is brought about by the modifications of the parameters of the flight plan, in particular if they are complex and at very short intervals, which obliges the pilot to recheck the consumption often, increases his task and multiplies the up and down movements between the head up and head down fields of view.